1. Field of the Invention
This invention relates to apparatus for making wafer blocks in which each of a plurality of consecutive coated wafer sheets is joined to the underside of an uncoated or coated wafer sheet.
2. Description of the Prior Art
In the industrial manufacture of wafer blocks which are filled, particularly with cream, it is known to bake large wafer sheets in a wafer-baking oven including revolving baking tongs, then to coat said wafer sheets with a cream layer in a contact coating operation or film coating operation, and to apply each coated wafer sheet with its upwardly facing cream layer to the underside of an uncoated or coated other wafer sheet to form a wafer block. Such wafer blocks built up in a downward direction have previously been formed by means of two helical conveyors, which were rotated about parallel axes in opposite senses and in which each wafer sheet was engaged on the underside by a laterally extending, single helical flight and was moved in a direction of travel against a stop and raised from a first level to a second, higher level and was thus applied to the cover sheet of the wafer block or to the lowermost wafer sheet of the partly formed wafer block, which top sheet or lowermost sheet is disposed on said second level. When a wafer block has been completed, the stop is lowered and the wafer block is moved from the second level in the direction of travel to a delivery conveyor, which succeeds said stop.
Said wafer blocks are moved in the usual manner under a pressure roller and are then cooled and are cut by means of known wafer blocks slicers to form the commercially available sliced wafer products. Wafer material in a width of about 5 to 10 mm must be removed from the edges of the wafer block as waste to ensure that broken out edges of the wafer sheets and uncoated wafer sheet portions near the edges of the wafer block will not influence the weight of each package of the sliced wafer block product.
The known block-forming apparatus in which each wafer sheet is engaged on its underside only by two helical flights extending from opposite sides in highly satisfactory if the length of the wafer sheets measured transversely to the direction of travel does not exceed a certain upper limit. The width of each wafer sheet is measured transversely to its length and is about two-thirds of its length. The diameter of the helical flights supporting the wafer sheets is approximately as large as the width of each wafer sheet. In that case each wafer sheet will be supported by the helical flights at two points, each of which is spaced about one-third of the length of the wafer sheet from the adjacent end of the wafer sheet. If the ratio of the length of each wafer sheet (measured transversely to the direction of travel) to its width exceeds 1.5 and amounts to 2 or more, the cream-coated wafer sheet may not be adequately supported in its intermediate portion and may break owing to its own weight or may sag to such an extent that it will hinder or prevent the feeding of the next following wafer sheet into the block-forming apparatus. Both occurrences are intolerable for a statisfactory operation of the block-forming apparatus.
One of the reasons for the trend towards larger wafer sheets is the desire to reduce the proportion of waste formed when a wafer block is sliced to form a sliced wafer block product so that a higher productivity of labor can be achieved.
But considerations of baking technology have permitted an increase of the size of a wafer sheet only in its length but not in its width because in case of an increase in width the wafer sheet could not be adequately outgassed so that it would be useless.
Another reason why the known block-forming apparatus having only two helical flights is not satisfactory is due to the fact that the public desires wafer sheets having a very low specific gravity, i.e., very delicate wafer sheets, which necessarily have only a low strength so that the problems described hereinbefore will arise when such wafer sheets are coated with heavy and thick cream layers and are processed.
Whereas that problem might be solved by the provision of helical flights which are larger in diameter, the increase of the diameter of the helical flights is necessarily limited by the small width of the wafer sheet.